Will there be magical Chain Shirt types with no reflex penalty and no spell failure chance, for the wizard to use? IE, stuff that you are automatically proficient in it, and can use it alright, no matter what?

Mail means any armour set made with rings. But the actual name doesn't matter. The idea is to use the name 'shirt' for all light armour, 'mail' for all medium armour and 'plate' for all heavy armour. I think that simplifies things.

Will there be magical Chain Shirt types with no reflex penalty and no spell failure chance, for the wizard to use? IE, stuff that you are automatically proficient in it, and can use it alright, no matter what?

As a general rule, no. As a special item (artifact), yes why not. For wizards, there will be bracers of armour and (probably) magic robes.

'Say there is a chunk of meat. Pirates will have a banquet and eat it! But heroes will share it with other people. I want all the meat!!' - Luffy in One Piece

I meant as a special item for wizards. It might not have to be the exact same as the one that people use in normal 3.5e games, but it can at least reference the name and stuff, maybe? 'This fey-crafted enchanted mithril shirt is so light that it doesn't restrict movements in any way -- not even for people who need to cast arcane spells, or even people without proficiency in armor. It is, apparently, lighter than some normal clothing!' or something like that.

Further, I have an item idea that can be the be-all, end-all item in this game:

That thing is totally one of the better items in the entirety of the SRD!

It would be totally awesome if some game, somewhere, provided a decent selection of polymorph forms in D&D that actually had utility, at high levels of play. Maybe have it be a major macguffin. Rather than a magic sword -- something like this recognizes the true potential of D&D...

Yes, this is good. There would be only one in the whole module or campaign.

Polymorphing is just too complicated in my opinion.

My problem with this is that, as written, these options are SUBSTANTIALLY cheaper than Bracers of Armor or Enchanted Robes, which are really expensive. That was why they are suggested as good options -- BECAUSE they are thousands of gold cheaper, and thus easier to get.

Mmm, no, spell failure means a wizard is better off not wearing traditional armour, unless he has taken certain feats to avoid the spell failure risk.So the more armour types there are that don't have any spell failure, the less meaningful the feats and non-traditional armour types become.Mage Armor requires spending a spell slot and it's limited to a certain amount of AC bonus, so it's not as good.

'Say there is a chunk of meat. Pirates will have a banquet and eat it! But heroes will share it with other people. I want all the meat!!' - Luffy in One Piece